StockControl - Fix

using System;
using System.IO;
using System.Collections.Generic;
using System.Text;
using System.Xml;
using System.Xml.Serialization;

// using DansCSharpLibrary.Serialization;

namespace StockControl
{
    class MainClass
    {
        static void Main()
        {
            PrincipalMenu();
        }

        static void PrincipalMenu()
        {
            bool _activated = true;
            do
            {
                Console.WriteLine("1) Add stock. \n2) Add sales. \n3) Check stock." +
                                  "\n4) Clear stock. \n5) Manage brands. \n6) Exit.");


                var input = Console.ReadKey();
                Console.WriteLine();
                switch (input.Key)
                {
                    case ConsoleKey.D1:
                        {
                            var newBeer = new Beer(1, true);
                            break;
                        }
                    case ConsoleKey.D2:
                        {
                            break;
                        }
                    case ConsoleKey.D3:
                        {
                            var newBeer = new Beer(3, false);
                            break;
                        }
                    case ConsoleKey.D4:
                        {
                            var newBeer = new Beer(4, true);
                            break;
                        }
                    case ConsoleKey.D5:
                        {
                            ManageBrands();
                            break;
                        }
                    case ConsoleKey.D6:
                        {
                            _activated = false;
                            Console.WriteLine("Closing application");
                            break;
                        }
                }
            }
            while (_activated == true);
        }

        public static void ManageBrands()
        {
            bool _activated = true;

            do
            {
                Console.Clear();
                Console.WriteLine("Press 1 to add brand. \nPress 2 to modify brand" +
                                  "\nPress 3 to delete brand. \nPress 4 to exit to menu.");

                var input = Console.ReadKey();
                switch (input.Key)
                {
                    case ConsoleKey.D1:
                        {
                            Console.Clear();
                            var newBeer = new Beer(true);
                            break;
                        }
                    case ConsoleKey.D2:
                        {
                            Console.Clear();
                            var newBeer = new Beer(2, true);
                            break;
                        }
                    case ConsoleKey.D3:
                        {
                            break;
                        }
                    case ConsoleKey.D4:
                        {
                            _activated = false;
                            break;
                        }
                }
            } while (_activated == true);
            Console.Clear();
        }
    }

    // [XmlAttribute()]

    [XmlRoot()]
    public class Menu
    {
        [XmlElement()]
        public List<Beer> Brands { get; set; }
    }

    [XmlRoot()]
    public class Beer
    {
        public static List<Beer> brands = new List<Beer>();

        [XmlAttribute()]
        public string name { get; set; }

        [XmlAttribute()]
        public int beers { get; set; }

        [XmlAttribute()]
        public int beerCases { get; set; }

        [XmlAttribute()]
        public int beerInCase { get; set; }

        public Beer() : this(false)
        {
        }

        public Beer(bool input)
        {
            if (input)
            {
                Console.WriteLine("Write the name of the new brand:");
                name = Console.ReadLine();
                Console.WriteLine("You have registered the {0} brand.", name);
                CheckData(1);
                Continue();
            }
        }

        public Beer(int _x, bool input)
            : this(input)
        {
            Console.Clear();
            CheckData(2);
            Console.WriteLine("Select a brand:");
                for (int _n = 0; _n < brands.Count; ++_n)
                {
                    int _y = _n + 1;
                    Beer _actualBrand = brands[_n];
                    string nameOfBrnd = _actualBrand.name;
                    Console.WriteLine("{0}) {1}", _y, nameOfBrnd);
                }
                switch (_x)
                {
                    case 1: //instantiate to add stock
                        {
                            int _UsInpt = Convert.ToInt32(Console.ReadLine());
                            brands[(_UsInpt - 1)].AddCase();
                            break;
                        }
                    case 2: //instantiate to change settings
                        {
                            int _UsInpt = Convert.ToInt32(Console.ReadLine());
                            brands[(_UsInpt - 1)].Settings();
                            break;
                        }
                    case 3: //instantiate to show brand
                        {
                            int _UsInpt = Convert.ToInt32(Console.ReadLine());
                            brands[(_UsInpt - 1)].Show();
                            break;
                        }
                    case 4: //instantiate to clear data/all data
                        {
                            Console.WriteLine("{0}) Clear all data", (brands.Count + 1));
                            int _UsInpt = Convert.ToInt32(Console.ReadLine());
                            if (_UsInpt == (brands.Count + 1))
                            {
                                ClearData(2);
                            }
                            else
                            {
                                brands[(_UsInpt - 1)].ClearData(1);
                            }
                            break;
                        }
                }
        }
        // I also tried saving/loading outside the class...
        public static void Load()
        {
            var menu = FileMenu.Load("Data.xml");
            brands = menu.Brands;
        }
        public static void Save()
        {
            var menu = new Menu() {Brands = brands};
            FileMenu.Save("Data.xml", menu);
        }
        // I'm using Daniel Schroeder's (aka deadlydog) serializaton.
        public void CheckData(int x)
        {
            switch (x)
            {
                case 1:
                    {
                        if (File.Exists("Data.xml"))
                        {
                            Load();
                            brands.Add(this);
                            Save();
                        }
                        else
                        {
                            brands.Add(this);
                            Save();
                        }

                        break;
                    }
                case 2:
                    {
                        if (File.Exists("Data.xml"))
                        {
                            Load();
                        }
                        else
                        {
                            NoBrand();
                        }
                        break;
                    }
            }
        }
        public void Settings()
        {
            bool activated = true;
            do
            {
                Console.Clear();
                Console.WriteLine("{0}\n1) Change name.\n2) change beers in a case.\n3) Exit settings.", name);
                var input = Console.ReadKey();
                switch (input.Key)
                {
                    case ConsoleKey.D1:
                        {
                            Console.WriteLine("Write the new name:");
                            string beername = Console.ReadLine();
                            name = beername;
                            Save();
                            Console.WriteLine("You have succesfully changed the name to {0}.", name);
                            Continue();
                            break;
                        }
                    case ConsoleKey.D2:
                        {
                            CaseContainer(1);
                            break;
                        }
                    case ConsoleKey.D3:
                        {
                            activated = false;
                            break;
                        }
                }
            } while (activated == true);
        }
        public void CaseContainer(int x)
        {
            switch(x)
            {
                case 1:
                    {
                        Console.Clear();
                        Console.WriteLine("How many beers a {0} case contains?", name);
                        beerInCase = Convert.ToInt32(Console.ReadLine());
                        Save();
                        break;
                    }
                case 2:
                    {
                        beerInCase = Convert.ToInt32(Console.ReadLine());
                        Save();
                        Console.WriteLine("{0} case: {1} beers.",name,beerInCase);
                        break;
                    }
            }
        }
        public void ClearData(int _x)
        {
            switch (_x)
            {
                case 1:
                    {
                        beers = 0;
                        beerCases = 0;
                        Save();
                        Console.WriteLine("You have cleared all {0} data.",name);
                        break;
                    }
                case 2:
                    {
                        Console.WriteLine("Are you sure you want to clear all data?" +
                                          "\n(This includes all brands)");

                        var _Input = Console.ReadKey();
                        /*while (_Input.Key != ConsoleKey.D1
                               || _Input.Key != ConsoleKey.D2) { }*/
                        switch (_Input.Key)
                        {
                            case ConsoleKey.D1:
                                {
                                    brands.Clear();
                                    Console.WriteLine("You have succesfully clear all data.");
                                    Save();
                                    break;
                                }
                            case ConsoleKey.D2:
                                {
                                    break;
                                }
                        }
                        break;
                    }
            }
            Continue();
        }
        public void NoBrand()
        {
            Console.WriteLine("Sorry, you don't have any brand yet." +
                    "\nPress <enter> to add a new brand or <space> to continue.");
            var _Inp = Console.ReadKey();

            //Code below not working
            /*while (Console.ReadKey().Key != ConsoleKey.Enter
                || Console.ReadKey().Key != ConsoleKey.Spacebar) { }*/
            switch (_Inp.Key)
            {
                case ConsoleKey.Enter:
                    {
                        var newBeer = new Beer(true);
                        break;
                    }
                case ConsoleKey.Spacebar:
                    {
                        Console.Clear();
                        break;
                    }
            }

        }
        public void AddCase()
        {
            if (beerInCase == 0)
            {
                Console.WriteLine("Before adding new cases, specify how many beers fit in a {0} case.",name);
                CaseContainer(2);
            }
            Console.WriteLine("How many cases you want to add?");
            int _cases = Convert.ToInt32(Console.ReadLine());
            beers = beers + _cases * beerInCase;
            double _x = beers / beerInCase;
            beerCases = Convert.ToInt32(Math.Floor(_x));
            Save();
            Console.WriteLine("You succefully added {0} {1} cases.\nYour new stock of {1} is {0} cases.\n",
                              _cases, name);
            Continue();
        }
        public void Show()
        {
            Console.WriteLine(name +
                              "\nNumber of beers: {0}" +
                              "\nNumber of cases: {1}" +
                              beers, beerCases);
            Continue();
        }
        public void Continue()
        {
            Console.Write("Press <Space> to continue...");
            while (Console.ReadKey().Key != ConsoleKey.Spacebar) { }
            Console.Clear();
        }
    }

    [XmlRoot()]
    public class FileMenu
    {
        public static readonly Encoding Utf8Encoding = Encoding.UTF8;
        public static readonly XmlSerializer MenuSerializer = new XmlSerializer(typeof(Menu));
        public static Menu Load(string path)
        {
            using (var stream = new StreamReader(path, Utf8Encoding, false))
            {
                using (var reader = new XmlTextReader(stream))
                {
                    return MenuSerializer.Deserialize(reader) as Menu;
                }
            }
        }
        public static void Save(string path, Menu instance)
        {
            using (var stream = new StreamWriter(path, false, Utf8Encoding))
            {
                using (var writer = new XmlTextWriter(stream))
                {
                    MenuSerializer.Serialize(writer, instance);
                }
            }
        }
    }
}